Zip Samples

Code Reference / Zip Samples

How to use SharpZipLib to work with Zip files

These samples try to cover the range of situations you will encounter. You may need to combine parts of each sample for your application.

Table of Contents on this page

• Create a Zip with full control over content
• Create a Zip from/to a memory stream or byte array
• Create a Zip as a browser download attachment in IIS
• Unpack a Zip with full control over the operation
• Unpack a Zip, including embedded zips, and re-pack into a new zip or memorystream
• Unpack a zip using ZipInputStream (eg for Unseekable input streams)
• Download and Unpack a zip from an FTP server with recovery

Download and Unpack a zip from an FTP server with recovery

This example extends upon the previous, to provide for a recoverable FTP download and extract. Second draft.

public class FtpSample {

	public static void TestZipDownload() {

		// Create the FTP stream that takes care of restarting in event of failure.
		// This will hide any temporary problems from ZipInputStream
		//
		Stream ftpStream = new FtpDownloadStream("ftp://www.contoso.com/test.htm", "anonymous", "[email protected]");

		UnzipFromStream(ftpStream, @"c:\temp\out");
		ftpStream.Close();
	}

	// Insert the "UnzipFromStream" code from the sample, above.

}

// Implements a restartable Ftp Download and exposes the result as an uninterrupted stream.
public class FtpDownloadStream : Stream {
	private string _serverUri;
	private string _userName;
	private string _password;

	private FtpWebRequest _request;
	private FtpWebResponse _response;
	private Stream _responseStream;
	private int _totalDone;

	public Exception CaughtException;

	public FtpDownloadStream(string serverUri, string userName, string password) {
		_serverUri = serverUri;
		_userName = userName;
		_password = password;
	}

	private void StartFtpDownload() {
		// This can be replaced with the Http equivalents
		_request = (FtpWebRequest)WebRequest.Create(_serverUri);
		_request.Method = WebRequestMethods.Ftp.DownloadFile;
		_request.Credentials = new NetworkCredential(_userName, _password);
		_request.ContentOffset = _totalDone;		// for resume on failure

		_response = (FtpWebResponse)_request.GetResponse();
		_responseStream = _response.GetResponseStream();
		//if (_responseStream != null)
		//	_responseStream.ReadTimeout = 10000;	// Set timeout to 10 seconds for testing.
	}

	public override int Read(byte[] buffer, int offset, int count) {
		//
		int attempts = 0;
		while (attempts++ < 5) {	// Adjust the maximum attempts according to your needs
			if (_responseStream == null) {
				StartFtpDownload();
			}
			try {
				// This will throw a timeout exception if the connection is interrupted.
				// Will throw null exception if failed to open (start); this will also retry.
				int done = _responseStream.Read(buffer, offset, count);

				_totalDone += done;
				return done;
			}
			catch (Exception ex) {
				CaughtException = ex;
				// Close ftp resources if possible. Set instances to null to force restart. 
				Close();
			}
		}
		return 0;
	}

	public override void Close() {
		if (_responseStream != null) {
			try {
				_responseStream.Close();
				_response.Close();
			}
			catch {
				// No action required
			}
		}
		_responseStream = null;
		_response = null;
		_request = null;
	}

	// Implement the Stream methods
	public override void Flush() {
		throw new NotImplementedException(); 
	}
	public override long Seek(long offset, SeekOrigin origin) {
		throw new NotImplementedException();
	}
	public override void SetLength(long value) {
		throw new NotImplementedException();
	}
	public override void Write(byte[] buffer, int offset, int count) {
		throw new NotImplementedException();
	}
	public override bool CanRead {
		get { return true; }
	}
	public override bool CanSeek {
		get { return false; }
	}
	public override bool CanWrite {
		get { return false; }
	}
	public override long Length {
		get { throw new NotImplementedException(); }
	}
	public override long Position {
		get { throw new NotImplementedException(); }
		set { throw new NotImplementedException(); }
	}
}

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